This invention is directed to an automatic flush control system for a toilet. The invention has particular utility for use with an upflush toilet designed to flush waste water to a sewer line located above the waste outlet of the toilet although it is not limited to such a use as will be appreciated hereinafter.
A toilet of the upflush type is described in U.S. Pat. No. 3,334,358, issued Aug. 8, 1967 to H. W. McPherson. In the embodiment disclosed in connection with FIGS. 5 and 6 of this patent, a first water flow is directed for a period of time through an adapter near the base of the toilet to disintegrate and liquify the waste in the toilet. At the end of this time period a second water flow is directed through the adapter transverse to the outlet in the base of the toilet. This water serves to aid in pumping the waste water from the toilet to a sewer connection which can be located at an elevated level above the outlet of the toilet.
With a toilet of this type, the time period for the disintegration and liquifaction of the waste must be selected to be long enough to achieve the desired results but not so long as to cause overfilling of the toilet bowl and flooding of the surrounding area. This can accomplished manually by the user operating a valve control mechanism to switch from the liquifaction phase to the outflush phase at the appropriate time. However, it is desirable to make operation of the toilet automatic so that it is not necessary for the user to attend throughout the flushing operation. To this end a timing mechanism is conventionally provided that will cause the switchover to occur at a fixed preselected time in the process and will also terminate the flushout phase at the end of a fixed preselected time period. The time periods are normally determined by the manufacture to achieve the desired results under normal operating conditions. Provision is usually made to allow manual override by the user if desired or to avoid improper operation of the system. Such manual override is only effective if the user remains for the entire flushing operation which defeats some of the benefit of the automatic operation.
In a commercially available automatic flush valve of this type, the timing of switchover to the flushout phase is determined by equalization of pressure between two chambers of a slide valve, which equalization occurs by leakage of pressurized water from one chamber to the other through a small aperture provided for this purpose. While generally effective, the aperture can become clogged with buildup of minerals from the water which can have the effect of causing the initial liquifaction phase to be prolonged. If allowed to continue too long the toilet bowl can overfill during the liquifaction phase and cause flooding of the surrounding area. Correction of this problem can be an expensive and time consuming process usually requiring return of the valve unit to a repair facility during which time the toilet is out of service. Thus, in accordance with one aspect of the present invention it is desirable to provide an automatic control system for this purpose in which timing of at least the liquifaction phase is independent of conditions of the supply water. Additionally, and for similar reasons, it is desirable in accordance with another aspect of the invention that the duration of at least the liquifaction phase and preferably also the flushout phase be maintained relatively constant. If, for any reason, the particular operation is interrupted in the middle of the phase, it is highly desirable that provision be made to assure that re-initiation of the operation will not cause a complete recycling of the particular phase since it could cause overfilling if the liquifaction phase is involved and unnecessary waste of water if the flushout phase is involved.
It is therefore an object of the invention to provide an automatic flush system for a toilet of the general type described which is not adversely affected by conditions of the supply water.
It is a further object of the invention to provide an automatic flush system of the type described in which the active duration of either or both of the operating phases is maintained unchanged even if, for any reason, the operation of the phase is interrupted for any reasonable period of time.